HSQ shaping

The HSQ egress shaping uses the following objects:

• HSQ queue groups — An HSQ queue group comprises eight egress queues with two WRR groups. One HS queue group is allocated to each of the following:

  • an egress SAP

  • an egress network port

  • an egress access queue group instance

  • an egress network queue group instance

  • a subscriber egress (a single SLA profile instance in single HS SLA mode)

• primary shapers — A primary shaper is allocated for each secondary shaper because it is required in the hierarchy. It does not perform any QoS control except when allocated for subscriber egress configured with multiple SLA profile instances in extended HS SLA mode.

• secondary shapers — Secondary shapers provide an abstraction to be used for QoS control of traffic to a downstream device, such as an access node. Shaping can be performed on all traffic or on each scheduling class within the secondary shaper.

• ports — The traffic forwarded to each port can be shaped. In addition, traffic in each scheduling class within a port can be shaped individually or within a single WRR group.

Six scheduling classes are supported across all the preceding objects.

The egress QoS scheduling hierarchy is shown in Figure 1.

Figure 1. Egress HSQ IOM scheduling hierarchy

The available egress shaping encompasses:

• Per-queue or per-WRR group of queues

• per-HSQ queue group aggregate

• per-primary shaper aggregate

• per-secondary shaper aggregate

• per-secondary shaper per scheduling class

• per-port aggregate

• per-port per scheduling class